Initial Product Testing – Test Description Standard tests were used for the initial testing, to ensure the new product performed as expected compared to products widely used in the steel industry globally
Load carrying capacity - The property of a lubricant to form a film on the lubricated surface which resists rupture under given load conditions. Expressed as maximum load the lubricated system can support without failure or excessive wear.
For load carrying capacity the 4 ball test was selected, the most common tests are:
• ASTM D 2596 & DIN 51350-4 For wear protection the 4 ball tests were also chosen
• ASTM D 2266 & DIN 51350-5
The 4 ball test consists of four ball bearings arranged in the form of an equilateral tetrahedron. The basic elements of the tetrahedron are three balls held stationary in a pot to form a cradle in which the fourth ball or upper ball is rotated around a vertical axis under pre-selected conditions of loads.
Mechanical/Shear/Roll Stability – this is the ability of grease to resist changes in consistency when subjected to mechanical work. The most common laboratory tests used to evaluate shear stability are:
• Worked penetration (extended worked stability) ASTM D217 and DIN 51804
• Roll Stability Test ASTM D1831
Water Resistance – this is the ability of grease to withstand the effects of water with no change in its ability to lubricate. We evaluate this with three different procedures which complement each other:
• Water wash out test: ASTM D 1264
• Wet roll stability: ASTM D 1831 (modified in the presence of 10% water)
• Water spray off test ASTM D 4049
Corrosion inhibition - In wet applications such as in a steel mill environment, the lubricants are expected to protect against corrosion. Two tests were considered in our test program • Rust test ASTM D 1743
• Emcor Rust Test ASTM D 6138; DIN 51802 Figure 1
Figure 2 shows results obtained from the water washout test. A limit was set at 2.0% weight loss, and most greases gave satisfactory results. The process waters had a wider influence on the performance of the individual greases in this test.
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These tests were conducted using process / cooling water from three different steel plants. Castrol tested a total of nine commercially available products (named as CAP in the following table), based on different thickening systems. All passed the tests successfully with standard tap water.
Figure 1 below shows the results for water spray off. Limits were agreed to exclude any products that did not show outstanding results; the cut off point was 30% loss after the test duration Most greases had similar performance in all three process waters, but two greases showed promising results; the Castrol development product and one of the commercially available products, CAP7.
Benchmarking Initial tests are carried out to ensure that new products meet the expectations of modern applications. Specialist lubricants usually require additional benchmarking before field trials can commence, and tests need to be more severe compared to standard lubricants
Castrol benchmarked performance against other commercially available products with similar performance characteristics, then conducted additional tests more relevant to steel mill environments:
• Water wash out • Water spray off • Roll stability • Rust test
LUBE MAGAZINE NO.123 OCTOBER 2014
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